Circular knitting machine comprising a fabric draw off device

ABSTRACT

A circular knitting machine comprises a fabric draw off device rotating with a rotary knitting assembly, said device including diametral traction rollers about which the knitted fabric is driven tangentially. The traction rollers are positively driven by a mechanical transmission device including a gear box with an input pinion driven by a rotary crown of said assembly, two exchangeable gears, and an output pinion the speed of which can be varied, as a function of the length of the fabric produced per turn of the machine, by choice of said exchangeable gears.

United States Patent Bourgeois 1 1 Nov. 26, 1974 [5 CIRCULAR KNITTINGMACHINE 463,788 11/1891 Hose et al 66/151 COMPRISING A FABRIC DRAW on:3,415,081 12/1968 Anderson 66/151 DEVICE Prima Examiner-W. C. Re nolds ll W Y [75] nventor lglpg'rllicegt Pau Bourgeois Troyes AssistantExaminer /& M. Falik Attorney, Agent, or Firm-Wenderoth, Lind & Ponack[73] Assignee: Etudes et Bonneterie S.A.,

Lausanne, Switzerland [22] Filed: Sept. 18, 1972 [57] ABSTRACT Acircular knitting machine comprises a fabric draw [21] Appl 289881 offdevice rotating with a rotary knitting assembly, said device includingdiametral traction rollers about [30] Foreign Application Priority Datawhich the knitted fabric is driven tangentially. The Nov. 9, 1971Switzerland 16270/71 traction rollers are Positively driven y amechanical transmission device including a gear box with an input 52U.S. c1. 66/151 pinion driven y a rotary Crown of Said assembly, two[51] Int. Cl D04b 15/88 exchangeable gears, andan Output Pinion theSpeed of 58 Field 61 Search 66/149 R, 151, 153 which can be varied, as afunction of the length of the fabric produced per turn of the machine,by choice of 5 R f en e Cited said exchangeable gears.

UNITED STATES PATENTS Bradford 66/151 4 Claims, 4 Drawing FiguresPATENTE; W26 1974 3,850,012

sum 1 er a PAIEN'IL33265374 3 850,012

SHEH 2 OF 3 26 I Fig. 2

PATEMTE Elm/261974 SHEET 3 UP 3 CIRCULAR KNITTING MACHINE COMPRISING AFABRIC DRAW OFF DEVICE The invention relates to circular knittingmachines of the type comprising a rotary assembly including at least oneneedle bed and a fabric draw off device rotating with said assembly,said draw off device including at least one traction roller disposed ina diametral plane of the machine and upon which the knitted fabric isdriven tangentially.

On circular knitting machines it is known to use a rotary fabric drawoff device driven in synchronism with the elements carrying the knittingmembers, the draw off device generally comprising several tractionrollers disposed parallel to one another and generally diametrally ofthe machine. These rollers are rotatably mounted on the draw off deviceand a tube of fabric formed by the knitting members engages between therollers in the form of a rectilinear sheet of doubled thickness which isdriven tangentially about the rollers and is then, in most cases, rolledflat on a rotating shaft of a winding mechanism. The part of themechanism controlling the rotation of the traction rollers is alsoprovided with adjustment means enabling modification of the speed of thetraction rollers as a function of the rate of production of the fabricon the knitting members.

In most known machines of this type, rotation of the traction rollersresults from the relative movement between the assembly of the draw offdevice and the stationary parts of the machine.

In certain cases, a friction device is mounted on the rotary draw offdevice, this friction device being adjustable to allow modification ofthe speed of rotation of the traction rollers. The transmission includesa driving element which is controlled, during rotation of the rotaryassembly of the machine, by a stationary toothed crown, and a drivenelement which is connected by gears to the rollers to be controlled, thefriction device being adjusted by the movement of a counterweight.

Because of the conception of such mechanisms, a sliding is producedbetween the various element of the friction device and thus does notenable the fabric to be driven at a constant speed by the tractionrollers.

In another type of known mechanism, two ratchet wheels with blockingrollers are mounted opposite one another at the ends of one of thetraction rollers and are urged, during rotation of the rotary assembly,by arms which move on an inclined stationary camforming ring theinclination of which is adjustable to enable setting of the speed ofrotation of the roller.

Since for this type of mechanism the two ratchet wheels with blockingrollers operate alternately, the traction roller is rotatedintermittently and its rotation is, moreover, not constant for allpositions of the rotary draw off device in relation to the inclinedcontrol ring. The consequence of this drawback is particularlyemphasized in large-output multisystem machines where the length ofknitted fabric produced per turn of the machine is relatively great.

Another disadvantage common to these different types of mechanismresides in the difficulty of obtaining a given adjustment of the speedof traction of the fabric, since in effect it is difficult for theoperator to return with high precision to a previous setting.

The present invention aims to remedy these disadvantages and to providethe traction roller(s) with a continuous rotation, ie which does notinvolve the problems inherent when the rotation is intermittent, andwith a speed exactly proportional to that of the rotary assembly of themachine, independent of the speed of rotation of the traction roller(s),whatever may be the position occupied by the rotary draw off devicerelative to the main frame of the machine.

According to the invention, a circular knitting machine comprises arotary assembly including at least one needle bed and a fabric draw offdevice rotating with said assembly, said traction device including atleast one traction roller disposed generally diametrally of the machineand upon which roller the knitted fabric is driven tangentially,mechanical means forming an uninterrupted kinematic chain for positivelydriving the traction roller(s) from a driving element rotatably drivenby another element rotating in synchronism with said assembly and drawoff device, and means for enabling the speed of the driving element tobe adapted as a function of the length of fabric produced per turn ofthe machine.

The accompanying drawings show, by way of example, an embodiment of theinvention as well as a variation. In the drawings:

FIG. 1 is a perspective view of the lower part of a circular knittingmachine schematically showing the fabric draw off device as well as acontrol mechanism for the traction rollers;

FIG. 2 is a perspective view of a part of the control mechanism of FIG.1;

FIG. 3 is a cross-section taken along line X-X of FIG. 2; and

FIG. 4 is a view similar to FIG. I showing a varied form of controlmechanism.

The circular knitting machine partially shown in FIG. 1 comprises arotary assembly provided with one or two needle beds (not shown) and adevice 1 for drawing down and winding of fabric produced by the needles.This draw off device 1 includes at its upper part three traction rollers2, 3, 4 disposed parallel to one another, generally diametrally of themachine, in a plane perpendicular to the axis of rotation of saidassembly. Said draw off device I is fixed on a rotary toothed crown 5coaxial to the rotary assembly and disposed at the base of a stationaryframe 6 of the machine, the crown and the rotary assembly being rotatedat the same speed driving means, not shown. The traction rollers couldalso be disposed diametrally but at different levels.

The fabric produced forms a tube 7 which engages, in the form of arectilinear sheet of double thickness, between the roller 2 and thecentral roller 3 about which it passes and then engages between thiscentral roller 3 and roller 4, from where it is wound on a rotatingshaft 8 of a winding mechanism of a type well known to these skilled inthe art, the details and mode of control of which do not fall within theambit of the invention and are therefore not shown.

Traction of the fabric by the rollers 2, 3, 4 takes place tangentially,and the rotation of the three rollers is controlled from rotation of thedraw off device with said rotary assembly by means of the followingelements which form a differential in a kinematic chain with positivedrive comprising a transmission with differential movement.

A gear train 9 carried by a support integral with stationary frame 6comprises a driving pinion ll meshing with the teeth of the rotary crown5. Pinion 11 is coaxially connected to a second pinion 12 driving, bymeans of an intermediary pinion 13, a pinion 14 of a pair of coaxialintegral pinions 14, 15. Pinion 15 meshes with a pinion 16 on the shaftof which is keyed a chainwheel 17.

Chainwheel 17 is connected by a chain 18 to a chain- 1 wheel 19 of apair of chainwheels 19, 20 joined by a sleeve 39 passing through thebase of device 1, which sleeve is mounted about a central spindle, notshown, integral with the base of frame 6 and disposed coaxial with saidcrown and said rotary assembly. Chainwheel 20 is connected by a chain 21to a chainwheel 22 keyed on the lower end of a vertical shaft 23supported by the rotary draw off device. The upper end of shaft 23carries a worm 24 engaging with a worm wheel 25 mounted at one end oftraction roller 4, the rotation of rollers 2 and 3 being provided fromroller 4 by gears not shown.

As will be described in detail further on, pinions l2 and 14 of geartrain 9 are removably mounted on their shafts and can be exchanged forpinions with different numbers of teeth. Taking into account the ratiosdefined by the other gears and toothed wheels of the mechanism, it is ispossible, by a judicious combination of pinions 12 and 14, to obtain alarge range of rotational speeds for the traction rollers.

The different elements of-the described drive mechanism thus constitutean uninterrupted kinematic chain enabling the device to obtain, by apositive liason, a rotational speed of the traction rollers exactlyproportional to that of the rotary assembly of the machine, whatever bethe value of this speed.

Other advantages of the described machine, and particularly thoseresulting from the use of a crown wheel and a pair of sprocket wheels,coaxial to the crown wheel, constituting with the gear train, atransmission with differential, movement will be apparent from thefollowing explanation analysing the functional relationships between thevarious members of the control mechanism. For the purpose ofsimplification, the reference numbers of various members, are replacedby letters. Hence, the toothed crown 5, driving pinion 11, gears 12, 14,l5, l6 and 17 are respectively designated by A, B, C, D, E, F and G;double chainwheels 19, 20 and wheel 22 by H, J and K; the ratio betweenworm 24 and worm wheel 25 of the traction roller is designated by l/R;and the diameter of roller 4 by d. The expression turn of the machinemeans each rotation of the rotary assembly. i.e., ofthe elementscarrying the knitting members.

For each turn of the machine, toothed crown 5 and the assembly of thedraw off device including chainwheel 22, the worm gear 24, wheel 25 andthe traction rollers also make one turn about the central axis of themachine. The length l of fabric tangentially driven by the tractionrollers during one turn of the machine is given by the followingformula:

l=(A/B 'C/D'E/F'G/H l) 'J/K l/R'n'd,

the part J/K l/R 1r (1 of which may be expressed by k, a constantcharacteristic of the various members of the rotary draw off device.

The number n of turns of the double chainwheels H and J in the samedirection of rotation as toothed crown A, per turn of the latter, i.e.,for one turn of the machine, is expressed by:

n =A/B C/D E/F G/H this number of turns being dependant on the ratioA/B,

' defined by the pair of exchangeable pinions (C, D) of gear train 9.

The length of fabric driven tangentially by the traction rollers for oneturn of the machine is thus given by Selection of the ratio A/B bychoice of the interchangeable pinions C, D would enable the provision ofn l, in which case the rollers 2, 3 and 4 would not turn about theiraxes and the traction of the rollers on the fabric is therefore zero.

By employing a transmission having a differential movement, the meansfor enabling adaptation of the speed of the driving element F as afunction of the length of fabric produced per turn of the machine may bedisposed on a stationary part of the machine. It thus becomes possible,from small variations in the gear ratios of the gear train 9, to obtainlarge variations in the speed of rotation of the traction rollers, thisrotation being moreover exactly uniform even at very low speed.

The disposition and the features of the gear train 9 enable theprovision of a simple gear box, of low bulk and with easy access. Anembodiment of such a gear box, in accordance with the mechanism of FIG.1, is shown in detail on FIGS. 2 and 3.

A support 10, fixed on the stationary frame 6 and carrying the geartrain 9, has the form of a case provided with a cover 26 pivoting abouta pin 27. The input pinion 11, which meshes with crown 5, as well asreducing pinion 15 are disposed under the base of support 10 and arerespectively fixed on shafts 28, 29 which pass through the base ofsupport 10 to control the corresponding interchangeable pinions 12 and14 mounted so as to be axially removable on fluted ends of therespective shafts. The second reducing pinion l6 and chainwheel 17constitute an assembly rotatably mounted on a shaft 30 fixed belowsupport 10.

The intermediary pinion l3, rotatably connecting the removable pinionsl2 and 14, is freely rotatably mounted on a shaft 31. To facilitateexchange of pinions 12 and 14 of different diameters, no fixing meansfor shaft 31 are provided, but shaft 31 is simply held at its ends byjamming between the plane surface 32, defining the upper surface of thebase of support 10, and the pivoting cover 26 which is folded down andheld by a locking screw 33. So as to eliminate any risks of unwanteddisplacement of the pinion 13 during manipulation of the cover 26, apermanent magnet 34 is disposed at the base of shaft 31 and ensures aslight holding thereof on the surface 32.

Such an arrangement considerably facilitates the exchange of the variousremovable pinions l2 and 14, which may additionally include visualidentification means such as letters or numbers enabling a desiredrotational speed of the traction rollers to be rapidly obtained.

Each time that it is necessary to modify the speed of the tractionrollers, clamping of the interchangeable pinions 12, 14 produces amomentary interruption in the kinematic chain connecting the crown 5 tothe rollers. The fabric 7, submitted to a certain tension between theknitting members and the rollers, tends to free itself by reversing thedirection of rotation of the latter; the use of a worm gear withsuitably inclined worm 24 (FIG. 1) enables such a reversal to beprevented.

In the variation shown in FIG. 4, the differential movement is obtainedby a second toothed crown 35 concentric to the control crown 5 androtatably mounted thereon. Crown 35 is controlled by a driving pinion 36disposed at the output of the gear box 37 of which the input pinion 40meshes with the crown 5, and driving of shaft 23 of the draw off deviceis effected from rotation of crown 35 by means of pinion 38.

What is claimed is:

1. A circular knitting machine having a stationary frame and comprising:

a rotary assembly mounted on said stationary frame;

a fabric draw-off device mounted on said rotary assembly and rotatingtherewith, said drawoff device comprised of at least one knittingtraction roller operatively disposed substantially diametrically of saidrotary assembly, knitted fabric being tangentially driven thereon; and

mechanical transmission means operatively coupled between said rotaryassembly and said at least one knitting traction roller and forming anuninterrupted kinematic chain for positively driving said at least onetraction roller, said mechanical transmission means comprised of a firstrotary command element coaxially connected to said draw off device, androtating therewith, a second rotary command element coaxial to saidfirst rotary command element, means connected to said second commandelement and said at least one traction roller for transmitting rotationfrom said second command element to said at least one traction rollerand gear box means positioned on said stationary frame of the rotaryknitting machine and coupled to both said first and second rotarycommand elements for controlling said second rotary command element fromthe movement of said first rotary command element, said gear box meanscomprised of at least one pinion said at least one pinion beingremovably mounted there in and being interchangeable with a pinion of adifferent diameter to vary the rotative speed of said second commandelement.

2. The circular knitting machine of claim 1 wherein said first rotarycommand element is a crowned wheel, said second rotary command elementbeing comprised of a pair of coaxial chain wheels coupled together forrotation and wherein said gear box means further comprises a first chainwheel and a first chain, said chain being linked to said firstchainwheel and one of said pair of coaxially coupled chainwheels, andsaid means transmitting the rotation to said at least one tractionroller from said second rotary command element being comprised of asecond chainwheel placed on an end of a shaft supported by said drawoffdevice and having gear means at the other end thereof, the rotation ofsaid second chainwheel being transmitted to said at least one tractionroller through said gear means which is operatively positioned therefor,and a second chain linking said second chain wheel to the other of saidpair of coaxial coupled chainwheels.

3. A circular knitting machine according to claim 1 wherein said firstrotary command element is a first crown wheel and said second rotarycommand element is a second crown wheel coaxial to said first crownwheel, said gear box means comprises a first pinion coupled to saidsecond crown wheel, and said means for transmitting rotation to said atleast one traction roller from said second rotary command element beingcomprised of a second pinion coupled to said second crown wheel and ashaft having one end adjacent said at least one traction roller andsupported by said drawoff device and having gear means on said adjacentend operatively coupled to said at least one traction roller, saidsecond pinion being coupled to the opposite end of said shaft.

4. A circular kitting machine as recited in claim 1., wherein said gearbox means comprises two interchangeable pinions and a third intermediatepinion rotatably connecting said two interchangeable pinions, saidintermediate pinion freely fitted on a shaft, and locking meanscomprised of a fixed member and a movable member, said shaft of saidintermediate pinion being rigidly supported between said fixed andmovable members at a position within said gear box means de pending onthe diameters of the interchangeable pin-

1. A circular knitting machine having a stationary frame and comprising:a rotary assembly mounted on said stationary frame; a fabric draw-offdevice mounted on said rotary assembly and rotating therewith, saiddrawoff device comprised of at least one knitting traction rolleroperatively disposed substantially diametrically of said rotaryassembly, knitted fabric being tangentially driven thereon; andmechanical transmission means operatively coupled between said rotaryassembly and said at least one knitting traction roller and forming anuninterrupted kinematic chain for positively driving said at least onetraction roller, said mechanical transmission means comprised of a firstrotary command element coaxially connected to said draw off device, androtating therewith, a second rotary command element coaxial to saidfirst rotary command element, means connected to said second commandelement and said at least oNe traction roller for transmitting rotationfrom said second command element to said at least one traction rollerand gear box means positioned on said stationary frame of the rotaryknitting machine and coupled to both said first and second rotarycommand elements for controlling said second rotary command element fromthe movement of said first rotary command element, said gear box meanscomprised of at least one pinion, said at least one pinion beingremovably mounted there in and being interchangeable with a pinion of adifferent diameter to vary the rotative speed of said second commandelement.
 2. The circular knitting machine of claim 1 wherein said firstrotary command element is a crowned wheel, said second rotary commandelement being comprised of a pair of coaxial chain wheels coupledtogether for rotation and wherein said gear box means further comprisesa first chain wheel and a first chain, said chain being linked to saidfirst chainwheel and one of said pair of coaxially coupled chainwheels,and said means transmitting the rotation to said at least one tractionroller from said second rotary command element being comprised of asecond chainwheel placed on an end of a shaft supported by said drawoffdevice and having gear means at the other end thereof, the rotation ofsaid second chainwheel being transmitted to said at least one tractionroller through said gear means which is operatively positioned therefor,and a second chain linking said second chain wheel to the other of saidpair of coaxial coupled chainwheels.
 3. A circular knitting machineaccording to claim 1 wherein said first rotary command element is afirst crown wheel and said second rotary command element is a secondcrown wheel coaxial to said first crown wheel, said gear box meanscomprises a first pinion coupled to said second crown wheel, and saidmeans for transmitting rotation to said at least one traction rollerfrom said second rotary command element being comprised of a secondpinion coupled to said second crown wheel and a shaft having one endadjacent said at least one traction roller and supported by saiddraw-off device and having gear-means on said adjacent end operativelycoupled to said at least one traction roller, said second pinion beingcoupled to the opposite end of said shaft.
 4. A circular kitting machineas recited in claim 1, wherein said gear box means comprises twointerchangeable pinions and a third intermediate pinion rotatablyconnecting said two interchangeable pinions, said intermediate pinionfreely fitted on a shaft, and locking means comprised of a fixed memberand a movable member, said shaft of said intermediate pinion beingrigidly supported between said fixed and movable members at a positionwithin said gear box means depending on the diameters of theinterchangeable pinions.